In stock trading and other financial instrument trading markets, a trader may buy and sell instruments on behalf of a number of different clients and/or investment portfolios. When a trader transacts a trade, the number of instruments traded may not satisfy an outstanding trading demand for the clients or portfolios. In such a situation, there may be a need to allocate the instruments that are traded among the waiting clients or portfolios. Manual allocation of a trade can be a complex and time consuming process. Consequently, computer automated allocation of a trade is desirable. One solution to allocating a traded instrument is to include functionality in an Order Management System (OMS) to perform trade allocation. However, in existing OMSs, trade allocation features may be lacking or inadequate. One solution to this problem is to modify OMS software to add desired allocation features. As a practical matter, such modification may not be feasible. For example, software code for an OMS may be under control of a vendor and not modifiable, or a trading network may include a variety of different OMSs and, due to cost or other concerns, modification of each of the OMSs may not be possible. Consequently, non-OMS based trade allocation solutions are desirable.